$count:5;
$result:null !default;
@if $count > 0{
    $result:true;
}@else if $count < 0{
    $result:false;
}@else{
    $result:null;
}

$list:(1,2,3,4,3,2,1);
@each $item in $list{
    #div-#{$item}{
        z-index:$item;
    }
}

@for $i from 1 through 4{
    .item-#{$i}{
        z-index:$i;
    }
}

@for $i from 1 to 4{
    .item-#{$i}{
        z-index:$i;
    }
}

@while $count > 0{
    $count:$count - 1 !global;
}
